This has happened at times in the past and is happening again today:  Pro Channel EQ does nothing.
 
In thes case, I turned Pro Channel EQ on on an SI-Bass track.  No matter how extreme I set the EQ, there is no perceptible difference and the virtual light on the EQ does not flash to show signal received.
 
I have tried changing turning Post off and on, but that shouldn't matter since there are no other effects (like Melodyne) that would make a difference.
 
I feel I am missing something simple.
 
By the way, I did try splitting the instrument track and using the EQ on the audio track, but it still didn't work.  I was not expecting that to matter since I use Pro Channel EQ on instrument tracks all the time.
 
What's going on here?  Thanks.

Hallo, Konrad.  I'm just clutching at straws, but are all the bands turned on?  Is it only this one track?
 
What else is in the PC before/after it?  The light(by the on button of EQ) only comes on when signal reaches a certain level.  What happens if you boost the signal going in (with a comp or blank FX chain)?

Or if the project was created on a system before Pro Channel (using the Sonitus EQ?) then you nave to manually enable the PC Equalizer.

There are a few power buttons on the EQ 

Ive missed them before as well by having one and not the other turned on.

You have the main one on the PC Track, one on the Upper right of the EQ, and then the ones within the EQ for the individual Freqs IIRC they are marked(L, LM, M, etc...) 

Are they all lit up showing ON?

I did not figure this out but I did find a work around.

I can go to the preset folder, select a preset, and then the PC works as normal.  I can change the settings from there.

In answer to the questions, I did check to make sure the EQ was on, that bands were active, etc.  Neither the EQ nor the compressor would work until I loaded a preset.  Oddly, other tracks worked fine.  Something just seems to get confused in Sonar at times.  The work-around is fine (and it led me to discover a bunch of presets I did not know existed).

This used to be a common problem with the ProChannel, then they added a global power button, at the top right.  Make sure it is on, if it is, try turning off and on again.  Hopefully that will fix it for you.

I had the same problem just last week.  It was a quick project, was only on one track and I didn't have the time to troubleshoot in depth.  I just routed the track to a buss and applied EQ there.  Next time I'll try the channel preset idea.

OH this might come in handy. Once in a while, in my X2a, I run into the effects stopping on a track. WHat I have done in the past is copy the wave to another track and rebuild it. But i will try this.

Hmmmm   Ive never had the prob with it not doing anything.

The preset was going to be my next suggestion to see what happens  

Glad ya found a work around on it.

Are you running X1d Expanded or without Expanded?

X1d NOT Expanded.